Question about DHCP DNS and DDNS

James Jalbert jjalbert at
Thu Dec 18 14:51:16 UTC 2014

I am having a DDNS update issue I hope someone can help me with.

I have one server, running as both DHCP and DNS. DHCP is set up with fixed leases, as we track activity of machines, and need each machine to get the same IP address every time.
I use a mysql database, to store all my machine information, and a perl script that exports the data and converts it to the format that the DHCP config file wants. This is working and has been working great for years.

I have DNS setup so that it resolves only my internal network names and addresses. Any queries for other domains are forwarded to our ISP DNS servers. Again is and has been working great for years.

I have configured dynamic updates, so that upon DHCP handing out a lease, it update DNS with the information. Is and has been working for years

Now my issue. When I update information in my DHCP database, export it to the DHCP config, everything works great, machines get assigned new ips and all seems fine. However when you look at searching the network with software like Apple Remote Desktop, You see the machine host name, its ip address but it my show a completely different dns name, such as the machine that had that ip previous.

So in DHCP machine is fixed-leased to 192,168.1.100 and machine is fixed-leased to 192.168.101 and machine is fixed-leased to, if I move everything down say 1 so A is now B is 102 and so on, The DNS record for A and B are never updated to show the change, shows up as, but will have a dns name of

Does this make sense to anyone? any thoughts or ideas of what I can do to clean the dns record so the reflect DHCP changes?

Thanks for your help

James Jalbert
Network Administrator
Eastern Aroostook RSU #39 
Phone: 207-493-4246
E-Mail: jjalbert at

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